A motion blur problem can arise in those forms of optical data recorders in which the recording medium moves rapidly past the focused writing beam. If the pulse width is too long or the rise and/or fall time of the light beam modulator is too slow, the energy density incident upon the recording medium will be reduced, and the recorded spot size lengthened as a result of the recording medium motion during the switching time of the modulator. These effects increase writing power requirements and reduce data storage capacity. Reduction of motion blur by the use of very fast electro-optic modulators is possible, but that technique tends to be rather costly.